Anchors for fastening objects to building walls are known in various shapes. If exceptional loads are expected, spreading anchors are used, inter alia, which are very rigid fastening means and as such exhibit little resilience and thus lead to a rigid connection between the object to be fastened and the building wall. A rigid connection does not exhibit energy dissipating behavior.
From DE 40 14 522 A1 a fastening element is known for being anchored in a drilled hole in a concrete part, which is able to absorb impact loads such as those occurring upon severe vibrations or earthquakes in order to avoid chipping of the drilled hole or breaking of the bolt. The fastening element comprises a threaded bolt having a spreading cone at its free end, and a spreading sleeve with longitudinal slots which define spreading segments. The threaded bolt comprises a threaded portion, which continues well into the spreading sleeve, then a collar-shaped portion having the same diameter as the inner bore of the spreading sleeve, and finally a shallow necking in front of the spreading cone. The inner bore of the spreading sleeve has a cylindrical portion of increased wall thickness overlapping with the spreading cone, and the wall thickness is reduced over the shallow necking and merges into the initial wall thickness of the spreading sleeve. Thereby, a flat annular space is formed, into which the spreading cone may be deformed in the event of an axial overload, in order to absorb the impact overload. In this case, the threaded bolt will slip out of the spreading sleeve a bit, and the object to be fastened will be offset from the wall in which the fastening element is anchored. Only little energy is absorbed during the deformation of the spreading sleeve.
From DE 37 109 64 A, a fastening element is known for use in a drilled hole of a solid masonry, wherein a threaded bolt has a spreading body at its end and cooperates with a spreading sleeve having two consecutive spreading regions which are interconnected through a predetermined breaking region that breaks in case of an overload. In this way it is avoided that the fastening element becomes disengaged from the drilled hole, even upon excessive vibrations such as those occurring in case of earthquakes.
From DE 93 103 57 U a spreading anchor is known for being fastened in an anchoring bore, wherein a spreading portion of the anchor sleeve is expanded, with a backlash reserve formed by a thickness reduction of the wall recessed from the inside, which is plastically deformable upon gripping of the spreading portion of the anchor sleeve which results in a shortening of the anchor length.
In conjunction with spreading anchors, a damping device is known (DE 10 2008 063 580 A1), which is intended for attenuating impact loads such as in case of earthquakes. An elastomeric sleeve encloses the threaded bolt of the spreading anchor and is compressed when tightening the nut, so that the elastomeric sleeve is pre-stressed free of play in a bore of the component to be fastened.
Adhesively secured anchors are widely known (DE 202 01 927 U1, EP 1 936 212 A2).
From DE 32 20 460 C1, a rock anchor is known, which comprises a tension member having ends of mild steel and a central compliance zone of stainless austenitic steel, and an anchor plate to prevent the rock from breaking off in galleries and spaces in underground mining and tunneling constructions. The ends of the tension member are adhesively secured to the rock. To achieve a high adjustment force, the austenitic central portion of the anchor is strain-hardened.